Facebook & Messenger Hacked

My Facebook and Messenger was recently hacked. They sent dubious messages to all my contacts, and changed the email and telephone number connected. I believe via my cell number.
Luckily i received email notifications and was able to recover the next morning, removed the cell number, but did NOT re-add my own, just deleted their email, and added mine again.
How did they do it?

By all means respond via PM if necessary. We don't really want to broadcast their methods, but I am curious to find out how, and prevent it, as multiple friends have had the same issues this year

thanks
Kerry

 

It is common knowledge of techniques used for gaining control.
Main perpetrators are email phishing (looking official, whilst asking you to update credentials at clicked links),
Fake Apps that you have unknowingly installed on your cell.......yes! the App store and Google Play has them.
These apps often pose as photo editors, mobile games, or fitness monitors, and after downloading the app, users are required to enter their Facebook credentials to log in.......
Keylogging is also possible however unlikely unless others have physical / network access to your device.
Have a new email to start a new FB account in your normal name presence.
They wont help you recover old, you will be scammed if someone says they can.